This invention relates generally to data communication and processing, and more particularly the invention relates to a Node Loop Core for implementing the transmission protocol in a Fibre Channel Node Port and which is flexible in structure and in operation with a Node Loop Port Super Core for implementing the Fibre Channel Standard as adopted by ANSI.
The Fibre Channel Standard (FCS) as adopted by ANSI provides a low cost, high speed interconnect standard for workstations, mass storage devices, printers, and displays. The Fibre Channel (FC) is ideal for distributed system architectures and image intensive LANs and clusters. FC is media independent and provides multi-vendor interoperability.
Current FC transfer rates exceed 100 Mbytes per second in each direction. FC data transfer rates can also be scaled to 50, 25, and 12.5 Mbytes per second. The aggregate bandwidth is unlimited.
Fibre Channel technology provides a single interface that supports both channel and network connections for both switched and shared mediums. FC simplifies device interconnections and software, and reduces hardware costs since each device needs only a single FC port for both channel and network interfaces. Network, point to point, and peripheral interfaces can be accessed through the same hardware connection with the transfer of data of any format for the sending device buffer to the receiving device buffer.
FCS can also be implemented using a low-cost Arbitrated Loop configuration. The aggregate bandwidth is limited by the FC maximum bandwidth, but this is the best configuration for controlling disk arrays. The Node Loop Port (NL.sub.-- Port) provides the necessary functions for Arbitrated Loop.
FIGS. 1A-1D illustrate several topologies for implementing the Fibre Channel.
FIG. 1A illustrates a Point-to-Point topology. FIG. 1B shows a simple fabric topology. FIG. 1C shows a Closed Arbitrated Loop, and FIG. 1D illustrates an Open Arbitrated Loop. The fabric link in FIG. 1D uses circuit switching much like a telephone network. The FC creates multiple, temporary, direct connections that each provide full bandwidth. Further, the bandwidth can be expanded by adding more paths.
A Fibre Channel Fabric can be as simple as a single cable connecting two devices or as complex as a large number of FC switches incorporating both circuit and packet switching that connect up to 16,000,000 devices. A device attached to an FC fabric can transmit data to any other device and receive data from any other device attached to the fabric.
An FC fabric uses circuit switching much like a telephone network. The FC creates multiple, temporary, direct connections that each provide the full bandwidth. Each connection can use the entire bandwidth so it does not become congested by adding more workstations and peripherals. The bandwidth can be expanded by adding more paths.
The FC hardware routes the transmissions. A device connected to the fabric that wants to transmit requests connection to the receiving device. The FC attempts to route the call by querying the availability of the receiving device. If the device responds that it is available, the FC confirms the route back to the sending device. If the connection fails, the FC re-routes the transmission.
Setting up frequent connections is not time intensive (less than 10 .mu.s per connection).
Every Node Port logs in with the port to which it is attached, either an F.sub.-- Port or an N.sub.-- Port.
The Fibre Channel Standard includes bridges and routers that can simultaneously transport other data communications protocols, so already existing devices need only be enhanced by attaching adapters rather than being replaced. The FCS provides for new media technologies to be easily added. Currently the FCS provides interconnection to the following higher-level protocols:
FDDI (Fibre Distributed Data Interface) PA1 HIPPI (High Performance Parallel Interface) PA1 SCSI (Small Computer Systems Interface) PA1 IPI (Intelligent Peripheral Interface) PA1 IBM's Block Multiplexer Channel PA1 ATM (In process) PA1 Medical Imaging PA1 Engineering CAD PA1 Scientific Visualization PA1 Computer Generated 3D Animation and Full-motion Video PA1 Simulation PA1 Multimedia PA1 Video Conferencing PA1 Image-based Document Storage and retrieval PA1 Large Transaction Databases PA1 Off-site Large Volume Backups--decouples mass storage from CPU--simple, quick, offsite backup PA1 Communications Channels for Supercomputer Emulation (workstation clustering) PA1 Each frame is an indivisible unit of information used by the signaling protocol (FC-2) and there are four major FC-2 frame types: PA1 Device.sub.-- Data frames carry data of the upper level protocol type. PA1 Link.sub.-- Data frames which carry a built-in protocol called Link Services. PA1 Link.sub.-- Control frames which implement flow control, error detection, and error handling functions. PA1 Video.sub.-- Data frames which carry video data that is directed to a video buffer.
FC is a solution to the following applications that require large volume information storage and transfers:
These applications require data transfers up to Mbits per second (30 32-bit color 1024.times.768 pixel images per second) uncompressed. Most of the current connection technologies are unable to transfer data fast enough to meet these needs. Fibre Channel can transfer uncompressed video data at rates that can generate full-screen real-time color displays.
The following tables define the Fibre Channel Standard (FCS levels (layers).
______________________________________ FC Level Description Defines: ______________________________________ FC-0 Physical Optical and electrical parameters Interface for interfacing to a variety of physical media that operate over a wide range of data rates FC-1 Transmission Serial encoding, decoding, and Protocol error control (8-bit/10-bit code) FC-2 Signaling Frame structures and byte sequences (Framing) used by FC-4 to transfer data Protocol (transport mechanism) FC-3 Common a set of services that are common Services across multiple N.sub.-- Ports of an FC node FC-4 Mapping to Software mapping between the FC Upper-Level lower levels (FC-0,1,2,3) and the Protocols upper-level protocols (IP13, SCSI, IP etc.) ______________________________________
Following are brief definitions of some of the FCS Framing Protocol (FC-2) terminology.
Two possible FC frame formats with FC frames being separated from each other by at least six four-byte IDLEs.
Following are illustrations of two Fibre Channel frames with a table defining the frame fields:
______________________________________ SOF FHDR Payload CRC EOF or SOF FHDR OHDR Payload CRC EOF ______________________________________ Mnemonic Definition Size (Bytes ______________________________________ SOF Start of Frame 4 FHDR Frame Header 24 OHDR Optional Headers 64 or 0 Payload Data 2112 or 2048 CRC Frame Error Check 4 EOF End of Frame 4 ______________________________________
The following table shows the FC-2 Frame Header (FHDR) structure:
______________________________________ Word Byte 1 Byte 2 Byte 3 Byte 4 ______________________________________ 1 R.sub.-- CTL DESTINATION.sub.-- ID 2 Reserved SOURCE.sub.-- ID 3 TYPE F.sub.-- CTL 4 SEQ.sub.-- ID DF.sub.-- CTL SEQ.sub.-- CNT 5 OX.sub.-- ID RX.sub.-- ID 6 PARAMETER ______________________________________
The following table defines the FHDR R.sub.-- CTL routing bits.
______________________________________ R.sub.-- CTL[7:4] Frame Definition ______________________________________ 0000 FC-4 Device.sub.-- Data 0010 Extended Link.sub.-- Data 0011 FC-4 Link.sub.-- Data 0100 Video.sub.-- Data 1000 Basic Link.sub.-- Data 1100 Link.sub.-- Control All Others Reserved ______________________________________
FIG. 2 is a functional block diagram of the NL Core 10 and the Super Core 12 which implement the FC-1 and FC-2 transmission and signalling protocols of the Fibre Channel standard. Heretofore, these protocols have been implemented with application specific integrated circuits (ASIC) with a host computer. This structure requires large and complex logic and has proved to be limited in achieving the 80 Mbytes/sec sustained throughput required.
The present invention provides a Node Loop Core for use in a modular super core structure with an imbedded processor which supports a full-featured Fibre Channel operation at 80 Mbytes/second sustained throughput. The structure can be designed in an application specific integrated circuit with custom specific functions appended thereto.